Electrical isolation method improves cathodic protection

Journal Article · Fri Dec 01 04:00:00 EST 1995 · Pipeline and Gas Journal

OSTI ID:175977

Tachick, H N ^[1]

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1. Dairyland Electrical Industries, Inc., Oregon, WI (United States)

Pipeline companies require power for electrical equipment that is an integral part of a system that must be cathodically protected, such as steel line pipe. At points along such pipelines are pumping stations, metering facilities, motor operated valves and other electrical equipment. The standard method of cathodically protecting a pipeline is to electrically isolate the equipment to be protected and then apply a direct current (DC) potential of about {minus}1.0 volts with respect to ground. This negative potential prevents corrosion of the metals used in the equipment or pipe. One of the major problems faced by pipeline companies in attempting to cathodically protect equipment is due to a conflicting set of requirements. One requirement is that effective corrosion protection needs DC isolation of the equipment for maximum protection. Another is that all electrical equipment must be grounded through an effective grounding path in accordance with National Electric Code (NEC) Section 250-51. Therefore, it would be desirable if DC isolation from the power utility grounding system could be obtained by users of electrical equipment that requires cathodic protection. This article details how this can be done and, at the same time, remain in compliance with known applicable codes.

• OSTI ID: 175977
• Journal Information: Pipeline and Gas Journal, Journal Name: Pipeline and Gas Journal Journal Issue: 12 Vol. 222; ISSN PLGJAT; ISSN 0032-0188
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
03 NATURAL GAS
CATHODIC PROTECTION
ELECTRIC POTENTIAL
ENGINEERING
GAS UTILITIES
NATURAL GAS INDUSTRY
PETROLEUM INDUSTRY
PIPELINES
SAFETY STANDARDS